Release build, incrementing the version number and publishing to maven central repository

Prepare a release

First, “prepare” a release. Preparing a release ensures you have no checked out file and no SNAPSHOT dependencies. It changes the version in all pom.xml files to the release version. It then runs all the tests. If everything passes, the release version is committed to the SCM system and tagged. The version number is then updated in all the pom.xml files again, this time to the next development version. Finally, the changes are commited again to the SCM repository.

mvn release:prepare

ensure you have no uncommitted files in your workspace. Ideally, use a fresh workspace for the release process.

Answer the prompts with appropriate values for the tag, version, and new development version

release version should be something like 1.0.1

development version should be something like 1.0.2-SNAPSHOT

tag should be something like sketches-core-1.0.1

If the prepare has an error (the build will fail if any tests fail), run ‘mvn release:clean’ to clean up the generated files and reset the workspace. If the prepare needs to be rolled back (undone in the SCM system), run ‘mvn release:rollback’.

Perform a release:

Next, “perform” a release. Performing a release checks out the tagged release from the SCM system into a new directory, builds it, and then runs the configured deploy goals to publish the release to a maven repository (Maven central). Performing a release automatically enables the release-profile in maven, causing source and javadoc jars to be automatically created and published.

mvn release:perform

You can add the ‘-DdryRun=true’ option to test the release process without actually generating a release. dryRun is supported on both the prepare and perform steps.

Rollback a release

If a release has been prepared but not performed yet, the release can be rolled back. Rolling back a release resets the pom.xml version numbers and tags in the SCM system, effectively nullifying the release.

mvn release:rollback

A release cannot be rolled back if it has already been cleaned up (the release.properties file and other metadata removed).

Clean a release

If a release fails to prepare or crashs, it can leave various files behind. These can be cleaned up with a release clean.

mvn release:clean

JDK7 vs JDK8

The internal Memory package detects whether the methods unique to the Unsafe class in JDK8 are present; if not, methods that are compatible with JDK7 are substituted using an internal interface. In order for this to work, this library still needs to be compiled using jdk8 but it should be done with both source and target versions of jdk7 specified in pom.xml. The resultant jar will work on jdk7 and jdk8.